The invention relates generally to systems for monitoring a medical patient""s condition, and more particularly to monitoring systems including a water and gas separator system for removing liquid which has condensed from a patient""s exhalation gases.
During medical treatment of a patient, it may be desirable to monitor a patient""s exhalation and, in some instances, to analyze the exhalation gas composition. Monitoring of exhalation gases, for example, may be used in analysis of apnea conditions or in the analysis of exhalation of a patient that is under anesthesia. Typically, a patient""s exhalation is monitored by providing at least a portion of the patient""s exhalation to a suitable sensor or analyzer.
Accurate analysis of gases in a patient""s exhalation depends, in part upon the collection of the flow of exhalation gases without the introduction of factors that may distort results of the analysis. Introduction of contaminants into the flow, or other alteration of the exhalation gases in the monitoring system, may render analytical results that do not reflect the actual condition or near actual condition of the patient.
Because a patient""s exhalation is usually relatively humid, condensed liquid must be removed before the gases reach the sensor. Liquid, such as water, may condense as exhalation gases flow from a patient to the gas analyzer or sensor. Therefore, two possible sources of moisture contamination exist, i.e., entrainment in exhalation and re-entrainment of prior condensation into a subsequent stream of exhalation. Condensation can result in inaccurate readings at the sensor or analyzer. Additionally, collected condensation can interrupt the smooth flow of exhalation to the sensor, another possible distortion of the sensor operation. Further still, sensing devices used in patient monitoring systems, such as an infrared spectrometer, are often delicate and can be uncalibrated by liquid entering the sensor system.
In order to remove liquid from the exhalation to prevent distortion of the gaseous composition of exhalation (gas waveform developed by the sensor or analyzer) and to protect the sensor or analyzer devices, it has been known to place a liquid and gas separator or a moisture trap between the patient and the sensing device to separate liquid and/or moisture from the exhalation gases before it enters the sensing device.
Some prior art liquid and gas separator and/or moisture trap designs utilize a porous hydrophilic material to separate water vapor from a flow of exhalation gases. While hydrophilic materials may effectively remove a quantity of condensed moisture from a flow of humid gas, their use in some prior liquid and gas separator and moisture trap designs have introduced other problems. For example, hydrophilic materials are porous and include voids. Such prior art liquid and gas separators and moisture trap designs, using hydrophilic materials, remove moisture from exhalation by allowing the exhalation to pass in proximity with or through the hydrophilic material. These arrangements can alter the gaseous composition of the exhalation being monitored by allowing gases held in the porous hydrophilic material to become re-entrained and mixed with flow of exhalation. More specifically, the re-entrainment or mixing may be in the form of previously exhaled gas or sampled gas which had been held in the voids and later released into a subsequent stream of exhaled air or sampled gas, thereby distorting the gas content of that subsequent stream. Thus, when the stream reaches the sensor, it is not an accurate representation of the patient""s condition at that instant and therefore an erroneous gas waveform is produced by the sensing device or analyzer. The greater the volume of hydrophilic material exposed to the flow of exhalation, generally the greater volume of gas which can be stored therein and hence the greater volume of gas available to later contaminate the exhalation. Minimizing the volume of hydrophilic material used in some prior art designs can decrease the amount of such mixing, but can also undesirably decrease the capacity of the liquid and gas separator or moisture trap. Further, it is known in some prior art liquid and gas separator or moisture trap designs to utilize devices that are fully disposable or partially disposable. Utilizing fully disposable or partially disposable liquid and gas separator or moisture trap designs creates higher costs to consumers, such as patient""s, hospitals, or health care facilities. These costs may be reduced by utilizing reusable moisture traps or liquid and gas separators.
Accordingly, there is a need for a liquid and gas separator for removing condensed moisture from a flow of exhalation without substantially altering the gaseous composition of the exhalation. Further, there is a need to provide a liquid and gas separator system such that the liquid and gas separator device is reusable. Further still, there is a need for a water separator system that has an expanded capacity to contain condensed moisture from a patient""s exhalation thereby assuring that liquid will not pass through the liquid and gas separator and into the sensor. Yet further still, there is a need for a liquid and gas separator system that may be easily emptied, or cleaned during the course of a medical procedure.
An exemplary embodiment of the invention relates to a liquid and gas separator. The fluid and gas separator includes an inlet and an outlet. The fluid and gas separator also includes a first chamber coupled to the inlet. The first chamber has a drain aperture and a second chamber is substantially sealed around the first chamber. The first chamber receives a combined gas and liquid from the inlet, and separates at least some of the liquid from the gas. The liquid is deposited at the bottom of the first chamber. The liquid deposited at the bottom of the first chamber is subsequently transferred to the second chamber through the drain aperture.
Another exemplary embodiment of the invention relates to a gas analysis system utilized to separate liquid from a gas sample. The system includes a gas sample source providing a first gas sample. The first gas sample at least partially includes liquid introduced from the source in a gaseous or liquid form. The system also includes an inlet receiving the first gas sample. Further the system includes an outlet providing a second gas sample. The second gas sample being derived from the first gas sample. The second gas sample includes substantially no liquid. Further still, the system includes a gas analyzer coupled to the outlet and configured to analyze the content of the second gas sample. Yet further still, the system includes a first chamber coupled to the inlet. The first chamber has a drain aperture and a second chamber substantially sealed around the first chamber. The first chamber receives a combined gas and liquid from the inlet, and separates at least some of the liquid separates from the gas. The liquid is deposited at the bottom of the first chamber, and liquid deposited at the bottom of the first chamber is subsequently transferred to the second chamber through the drain aperture.
Still another exemplary embodiment of the invention relates to a liquid and gas separator system. The system includes an inlet receiving a first gas sample. The first gas sample at least partially includes liquid introduced from a patient in a gaseous or liquid form. The system also includes a first chamber coupled to the inlet and configured to receive the first gas sample. The first chamber has a drain aperture. Further, the system includes an outlet, coupled to the first chamber and configured to receive a second gas sample from the first chamber. The second gas sample being derived from the first gas sample. The second gas sample includes substantially no liquid. Further still, the system includes a second chamber substantially sealed around the first chamber. The first chamber receives a combined gas and liquid from the inlet, and separates at least some of the liquid from the gas. The first chamber is configured to have liquid deposited at the bottom of the first chamber, and liquid deposited at the bottom of the first chamber is subsequently transferred to the second chamber through the drain aperture.
Yet still another exemplary embodiment of the invention relates to a method of analyzing a gas sample. The method includes receiving a first gas sample into a first expansion chamber. The method also includes separating liquid from the first gas sample. Further, the method includes providing liquid from the first chamber to the second chamber through a drain aperture in the first chamber. Further still, the method includes providing a second gas sample from the first chamber to a gas analyzer.